These studies will focus upon the mechanism of granulosa cell maturation and luteinization in the pig and monkey. During follicular maturation there is an increase in LH-hCG receptors as well as in adenyl cyclase and an increase in ability to luteinize and secrete progesterone. The hormones and other intrafollicular agents which bring about this maturation will be investigated. Cells will be obtained from small immature follicles and cultured with suspected hormones such as FSH, insulin, cortisol, LH, estrogen, prostaglandins as well as in the presence of follicular fluid obtained from large follicles. After various times the amount of LH receptors, adenyl cyclase and ability to secrete progesterone will be estimated. Control of luteinization and granulosa cell steroidogenesis within the monkey follicle in vivo also will be investigated. LH levels within the follicular fluid of follicles of various size will be measured by a radioreceptor assay. Androgen and estrogen secretion by isolated granulosa, thecal and stromal cells will be examined in culture and in the isolated preovulatory monkey ovary in vivo. The action of a soluble luteinizing hormone binding inhibitor isolated from porcine corpus luteum upon granulosa cells will be examined in order to further understand the controls of the luteinization process.